eco-complete or aragonite?

I have both in different tanks, I can answer any questions you might have

Whcih do you prefer? I understand the eco-complete is darker and darker color substrate brings out colors in fish better, right? Which is better at PH buffering?

They both buffer to 8.3 in my tanks, the eco complete has aragonite in it for buffering so they should be the same as far as buffering. The eco complete is available in different colors, I got the sahara sand , which is the darker stuff, and yes, it does bring out some more color in the fish. I think the eco complete is also supposed to contain trace elements to better replicate the water conditions of the lakes. The eco complete is kind of expensive, but I think it's worth it, and if I was setting up another tank today, I would buy it again.

Does Eco-complete need pre-rinsed?

The bag says not to rinse. The water was only slightly cloudy for 24 hours without rinsing.

The eco-complete I got had water in it,so no,no rinsing,and like shellies215 said, slightly cloudy

Fantastic. I'll post pics when it's done. Thank you both.